Magneto contact plug



T. DUPLO April l, 1930.

MAGNETO CONTACT PLUG Filed Jan, 29, 1927 Patented Apr. 1, 1930 PATENT OFFICE THOMAS DUELO, OF CROGHAN, NEW YORK MAGNETO CONTACT PLUG Application filed January 29, 1927.

This invention relates to certain improvements in magneto contact devices as used more particularly in connection with the ignition systems of internal combustion engines of the Ford type.

The contact points or' devices of this character are usually made separate from the spring and spring pressed against the lead block of the magneto and in some instances are protected against accumulations of insulating or short-circuiting matter from within the magneto case by separate sleeves or guards surrounding' the contact points.

The main object of the present invention is l5 to make the contact point and spring in one piece and to coat the helices ot' the spring coil adjacent the contact point with insulating material as a permanent part thereof leaving the extreme inner end ot the spring wire exposed for direct Contact with the lead block of the magneto, thereby reducing to a minimum the number of parts and also the liabilityv of short circuits.

In the drawings Figure l is a side elevation of the magneto cont-act device embodying the various features of my invention showing al portion of the magneto case in section and also showing diagrammatically a partot the lead block ot the magneto.

Figure 2 is a longitudinal vertical sectional view of the detached magneto contact shown in Figure l.

Figure 3 is a side elevation of the detached coiled spring and its support and contact point together with the insulation coating for the closed helices of the coil adjacent the contact point.

As illustrated, this device comprises a bushing -1- having a reduced externally threaded lower end and a cylindrical bore therethrough from end to end for receiving an inner tubular lining -2- of insulating material which extends beyond opposite ends of the bushing nl to form opposite end shoulders -2- and 2- which engage opposite ends of the bushing for holding the insulating lining and bushing against relative axial movement.

The bushing -2- is adapted to be screwed Serial No. 164,500.

into a threaded opening am in the magneto casing A- but obviously may be used in connection with an adapter, not shown, but sometimes employed in devices oi' this character.

The interior bore in the inner end of the tubular lining -2- is of somewhat larger diameter than its outer end for receiving a spring coil -5- having a limited number of its helixes as 5- at its inner end in approximately closed relation and the remainder of its helices as -5 at its upper end in more or less open relation to allow resilient axial movement of the inner helices for the purpose of holding the extreme inner end of the inner coil in contact with the lead bloclr as A of the magneto when the device is adjusted for use.

A hollow plug 3 is secured in the outer end or head of the insulating lining` 2 and is provided with a reduced outwardly extending threaded stem -3- having a nut -4- which together with the` stem -8- constitutes a binding post for receiving the usual wire connection of the ignition circuit.

rlhe plug3- is provided with an annular groove -8-, Figure 3. for receiving an annular rib -2-' on the head -2- ofthe lining -2- as shown in Figure 2 for holding the plug and lining against relative axial movement.

The outermost helix of the coil -5-- is extended axially and secured in the central lengthwise opening in the plug -3- for holding the spring coil in operative position within the inner end of the insulating sleeve or lining -2-.

The closed helices -5- forming a part of the spring coil -5- are coated at -6- with an insulating material such as enamel which extends into the interior of the lining -2- and across the innermost helix of the spring coil so as to guard the coil against short circuits by material which may be thrown in contact therewith from the interior of the magneto case.

The extreme inner end of the coil is also extended axially and inwardly co-axial with the axis of the coil and surrounded circumferentially by portions of the insulating coating 6- leaving a relatively Small portion of the inner end of the coil exposed to form a Contact point -7- which is spring-pressed by the coil -5- into contact With the lead Vblock -A- of the magneto When the device is adjusted Jfor use for producing the necessary ignition for the internal combus tion engine.

The insulating coating which envelops the closed helices of the spring-coil -5- forms an insulating tie connecting those helices to give rigidity to this portion of the spring and to the contact point 7 While the open helices -5 aord the necessary resiliency to yieldingly hold the contact point -7- in engagement With the magneto lead block A-.

It Will be apparent from the foregoing description that the contact point -7-- forms an integral part of the spring coil -5- and that the axially extending end -5- also forms an integral part of the coil while the insulating coating -6- is permanently secured to the closed helices of the coil to tie the same together and to Jform a substantially unitary part thereof so that the coil, contact member and insulating coating are all supported from the upper extremity as -5- of the coil through the medium of the plug -3- thereby reducing the number of the parts and liability of short circuits and also producing an extremely flexible and highly efficient contact. a

What I claim is In a magneto Contact, a coil spring rigidly supported at one end and having its other end yieldingly held against the magneto lead, the helices adjacent the contact end of the coil being rigidly connected to each other by a covering of insulating material leaving the Contact point free from insulation.

In Witness whereof I have hereuntoset my hand this 25th day of January, 1927.

THOMAS DUFLG. 

